Harvesting and distributing a certificate based on a DNS name

ABSTRACT

According to certain embodiments, a delivery manager comprises an interface and processing circuitry. The interface is configured to receive a certificate that a Domain Name Service (DNS) associates with a DNS name of a recipient system. The processing circuitry is configured to distribute the certificate to a plurality of sending systems. Each sending system is configured to store the certificate in a local memory of the sending system, use the certificate from the local memory of the sending system to perform encryption in response to a future determination to send an encrypted message to the recipient system, and send the encrypted message directly to the recipient system.

FIELD OF THE INVENTION

Certain embodiments of the present disclosure relate, in general, tocertificates that may be used for securing computing systems and, morespecifically, to harvesting and/or distributing a certificate based on aDomain Name System (DNS) name.

BACKGROUND

In a computer network, a sender may transmit files, email messages, andother data to a recipient. The sender may encrypt the data to increasesecurity in some circumstances. As an example, the sender may encryptthe data using a public key encryption technique. In public keyencryption, two separate keys are associated with the recipient, apublic key and a corresponding private key. The sender obtains therecipient's public key, encrypts the data using the public key, andtransmits the encrypted data to the recipient. The recipient decryptsthe encrypted data using its corresponding private key.

SUMMARY

According to certain embodiments, disclosed is a delivery manager, amethod for use in a delivery manager, and a non-transitory computerreadable medium comprising logic for execution by a delivery manager.The delivery manager, method, and/or logic are configured to distributea certificate. For example, according to a first type of embodiments, acertificate associated with a recipient system is distributed to aplurality of sending systems so that the sending systems can sendencrypted messages to the recipient system. According to a second typeof embodiments, a certificate associated with a first endpoint may bedistributed to a plurality of other endpoints so that transport layersecurity can be established for a connection between the first endpointand one of the other endpoints. Examples of the first and second typesof embodiments are further summarized below. For simplicity, the firstand second types of embodiments are summarized separately. However, thedelivery manager, method, and/or logic can be configured to support bothtypes of embodiments.

With respect to the first type of embodiments, according to certainembodiments, a delivery manager comprises an interface and processingcircuitry. The interface is configured to receive a certificate that aDomain Name Service (DNS) associates with a DNS name of a recipientsystem. The processing circuitry is configured to distribute thecertificate to a plurality of sending systems. Each sending system isconfigured to store the certificate in a local memory of the sendingsystem, use the certificate from the local memory of the sending systemto perform encryption in response to a future determination to send anencrypted message to the recipient system, and send the encryptedmessage directly to the recipient system.

According to certain embodiments, a method for use in a delivery managercomprises receiving a certificate that a DNS associates with a DNS nameof a recipient system. The method distributes the certificate to aplurality of sending systems. Each sending system is configured to storethe certificate in a local memory of the sending system, use thecertificate from the local memory of the sending system to performencryption in response to a future determination to send an encryptedmessage to the recipient system, and send the encrypted message directlyto the recipient system.

According to certain embodiments, a non-transitory computer readablemedium stores logic that, when executed by processing circuitry of adelivery manager, is operable to cause the delivery manager to performactions. The actions comprise receiving a certificate that a DNSassociates with a DNS name of a recipient system and distributing thecertificate to a plurality of sending systems. Each sending system isconfigured to store the certificate in a local memory of the sendingsystem, use the certificate from the local memory of the sending systemto perform encryption in response to a future determination to send anencrypted message to the recipient system, and send the encryptedmessage directly to the recipient system.

Each of the above-described delivery manager, method, and logic mayinclude one or more additional features, such as one or more of thefollowing:

According to certain embodiments, the DNS name of the recipient systemcorresponds to an individual mail client.

According to certain embodiments, the DNS name of the recipient systemcorresponds to a mail transfer agent.

According to certain embodiments, the certificate is received from afirst sending system of the plurality of sending systems. The firstsending system configured to obtain the certificate from the DNS inreal-time when sending a message to the recipient system for which thefirst sending system does not have the certificate, and to provide thecertificate to the delivery manager for distribution to the othersending systems.

According to certain embodiments, the delivery manager/method/logicsends a request message from the delivery manager to the DNS. Therequest message requests the certificate associated with the DNS name ofthe recipient system. The certificate is received as a result of sendingthe request message. In some embodiments, the request message is sentaccording to DNS-based Authentication of Named Entities (DANE) protocol.

Certain embodiments include initiating a discovery procedure such thatthe request message is sent to the DNS without requiring the recipientsystem to inform the delivery manager that the certificate exists.

According to certain embodiments, the request message from the deliverymanager to the DNS is sent in response to a determination that thesending system failed to send the encrypted message directly to therecipient system. The determination that the sending system failed tosend the encrypted message directly to the recipient system can be madebased on data reported from the sending system.

According to certain embodiments, the recipient system is notified inresponse to the delivery manager determining that there is a problemwith the certificate received from the DNS.

According to certain embodiments, an invitation message is sent to therecipient system. The invitation message invites the recipient system tobecome a member of the plurality of sender systems. According to certainembodiments, the delivery manager maintains a certificate repositorycomprising other certificates associated with other recipient systems.In response to the recipient system becoming a member of the pluralityof sender systems, the other certificates are distributed to therecipient system.

Certain embodiments further comprise receiving a current certificatethat the DNS associates with the DNS name of the recipient system,determining that the current certificate differs from the previouscertificate, and distributing the current certificate to the pluralityof sending systems. The current certificate can be obtained byperiodically sending request messages to the DNS. The request messagesrequest the current certificate associated with the DNS name of therecipient system.

According to certain embodiments, the certificate is distributed to theplurality of sending systems according to a pre-determined time period.In some embodiments, the certificate is made available to the pluralityof sending systems concurrently.

According to certain embodiments, the certificate comprises a keyidentifier, a public key, information about a version, and/or asignature.

According to certain embodiments, distributed file version managementtechnology is used to distribute the certificate to the sending systems.

With respect to the second type of embodiments, according to certainembodiments, a delivery manager comprises an interface and processingcircuitry. The interface is configured to receive a certificate that aDNS associates with a DNS name of a first endpoint. The processingcircuitry is configured to distribute the certificate to a secondendpoint. The second endpoint is configured to store the certificate ina local memory of the second endpoint and, in response to a futuredetermination to establish a connection with the first endpoint, use thecertificate from the local memory of the second endpoint to establishtransport layer security (TLS) for the connection.

According to certain embodiments, a method for use in a delivery managercomprises receiving a certificate that a DNS associates with a DNS nameof a first endpoint and distributing the certificate to a secondendpoint. The second endpoint is configured to store the certificate ina local memory of the second endpoint and, in response to a futuredetermination to establish a connection with the first endpoint, use thecertificate from the local memory of the second endpoint to establishtransport layer security (TLS) for the connection.

According to certain embodiments, a non-transitory computer readablemedium stores logic that, when executed by processing circuitry of adelivery manager, is operable to cause the delivery manager to performactions. The actions comprise receiving a certificate that a DNSassociates with a DNS name of a first endpoint and distributing thecertificate to a second endpoint. The second endpoint is configured tostore the certificate in a local memory of the second endpoint and, inresponse to a future determination to establish a connection with thefirst endpoint, use the certificate from the local memory of the secondendpoint to establish transport layer security (TLS) for the connection.

Each of the above-described delivery manager, method, and logicassociated with may include one or more additional features, such as oneor more of the following:

According to certain embodiments, the DNS name of the first endpointcorresponds to an individual mail client.

According to certain embodiments, the DNS name of the first endpointcorresponds to a mail transfer agent.

According to certain embodiments, the certificate is received from athird endpoint. The third endpoint is configured to obtain thecertificate from the DNS and provide the certificate to the deliverymanager for distribution to other endpoints. For example, the thirdendpoint can obtain the certificate from the DNS in real-time whenestablishing a TLS connection to the first endpoint for which the thirdendpoint does not have the certificate.

According to certain embodiments, a request message is sent from thedelivery manager to the DNS. The request message requests thecertificate associated with the DNS name of the first endpoint. Thecertificate is received as a result of sending the request message. Insome embodiments, the request message is sent according to DNS-basedAuthentication of Named Entities (DANE) protocol.

According to some embodiments, a discovery procedure is initiated suchthat the request message is sent to the DNS without requiring the firstendpoint to inform the delivery manager that the certificate exists.

According to certain embodiments, the request message is sent inresponse to a determination that the second endpoint failed to establishTLS for the connection with the first endpoint. The determination thatthe second endpoint failed to establish TLS for the connection with thefirst endpoint can be made based on data reported from the secondendpoint.

According to certain embodiments, the first endpoint is notified inresponse to the delivery manager determining that there is a problemwith the certificate received from the DNS.

According to certain embodiments, an invitation message is sent to thefirst endpoint. The invitation message invites the first endpoint tobecome a member of a network comprising a plurality of endpoints. Inresponse to the first endpoint becoming a member of the network, othercertificates associated with other endpoints can be distributed from acertificate repository maintained by the delivery manager to the firstendpoint.

Certain embodiments receive a current certificate that the DNSassociates with the DNS name of the first endpoint. In response todetermining that the current certificate differs from the previouscertificate, the current certificate is distributed to the secondendpoint and a plurality of other endpoints.

According to certain embodiments, the current certificate is obtained byperiodically sending request messages to the DNS. The request messagesrequest the current certificate associated with the DNS name of thefirst endpoint.

According to certain embodiments, the certificate is distributed to thesecond endpoint and a plurality of other endpoints according to apre-determined time period.

According to certain embodiments, the certificate comprises a keyidentifier, a public key, information about a version, and/or asignature.

According to certain embodiments, the certificate is made available to aplurality of endpoints concurrently.

According to certain embodiments, distributed file version managementtechnology is used to distribute the certificate to the second endpoint.

Also disclosed is a sending system, a method for use in a sendingsystem, and a non-transitory computer readable medium comprising logicfor execution by a sending system. According to certain embodiments, asending system comprises an interface and processing circuitry. Theinterface is configured to receive a certificate that a DNS associateswith a DNS name of a recipient system. The certificate is received fromthe DNS or from a delivery manager located remotely from the sendingsystem. The processing circuitry is configured to provide thecertificate to the delivery manager (e.g., for distribution to othersending systems) in response to a determination that the certificate wasreceived form the DNS. The processing circuitry is operable to store thecertificate in a local memory of the sending system and, in response toa future determination to send an encrypted message to the recipientsystem, use the certificate from the local memory of the sending systemto perform encryption. The processing circuitry is operable to send theencrypted message directly to the recipient system.

According to certain embodiments, a method for use in a sending systemcomprises receiving a certificate that a DNS associates with a DNS nameof a recipient system. The certificate is received from the DNS or froma delivery manager located remotely from the sending system. The methodcomprises, in response to a determination that the certificate wasreceived form the DNS, providing the certificate to the delivery managerfor distribution to other sending systems. The method comprises storingthe certificate in a local memory of the sending system and, in responseto a future determination to send an encrypted message to the recipientsystem, using the certificate from the local memory of the sendingsystem to perform encryption. The method comprises sending the encryptedmessage directly to the recipient system.

According to certain embodiments, a non-transitory computer readablemedium storing logic that, when executed by processing circuitry of asending system, is operable to cause the sending system to performactions. The actions comprise receiving a certificate that a DNSassociates with a DNS name of a recipient system. The certificate isreceived from the DNS or from a delivery manager located remotely fromthe sending system. The actions comprise, in response to a determinationthat the certificate was received form the DNS, providing thecertificate to the delivery manager for distribution to other sendingsystems. The actions comprise storing the certificate in a local memoryof the sending system and, in response to a future determination to sendan encrypted message to the recipient system, using the certificate fromthe local memory of the sending system to perform encryption. Theactions comprise sending the encrypted message directly to the recipientsystem.

Each of the above-described sending system, method, and logic mayinclude one or more additional features, such as one or more of thefollowing:

According to certain embodiments, the DNS name of the recipient systemcorresponds to an individual mail client.

According to certain embodiments, the DNS name of the recipient systemcorresponds to a mail transfer agent.

According to certain embodiments, the sending system/method/logicdetermines that the sending system does not have the certificaterequired to encrypt a message to the recipient system and requests thecertificate from the DNS in real-time when sending the message to therecipient system. In some embodiments, the request message is sentaccording to DNS-based Authentication of Named Entities (DANE) protocol.

According to certain embodiments, a current certificate that the DNSassociates with the DNS name of the recipient system is received and adetermination is made that the current certificate differs from theprevious certificate. The current certificate is then provided to thedelivery manager for distribution to the plurality of sending systems.

According to certain embodiments, the certificate comprises a keyidentifier, a public key, information about a version, and/or asignature.

According to certain embodiments, updated certificates are periodicallyrequested from the DNS or the delivery manager according to apre-determined time period.

According to certain embodiments, distributed file version managementtechnology is used to receive the certificate from the delivery manager.

Also disclosed are first and second endpoints, a method for use in thesecond endpoint, and a non-transitory computer readable mediumcomprising logic the execution by the second endpoint. The secondendpoint/method/logic is configured to receive a certificate that a DNSassociates with a DNS name of the first endpoint. The certificate isreceived from the DNS or from a delivery manager located remotely fromthe second endpoint. In response to a determination that the certificatewas received from the DNS, the second endpoint/method/logic isconfigured to provide the certificate to the delivery manager fordistribution to other endpoints. The second endpoint/method, logic isfurther configured to store the certificate in a local memory of thesecond endpoint and, in response to a future determination to establisha connection with the first endpoint, use the certificate from the localmemory of the second endpoint to establish TLS for the connection.

The above-described second endpoint/method/logic may include one or moreadditional features, such as one or more of the following:

According to certain embodiments, the DNS name of the first endpointcorresponds to an individual mail client.

According to certain embodiments, the DNS name of the first endpointcorresponds to a mail transfer agent.

According to certain embodiments, the second endpoint/method/logicdetermines that the second endpoint does not have the certificaterequired to establish TLS for the connection to the first endpoint andrequests the certificate from the DNS in real-time when establishing theconnection to the first endpoint. In some embodiments, the requestmessage is sent according to DNS-based Authentication of Named Entities(DANE) protocol.

According to certain embodiments, a current certificate that the DNSassociates with the DNS name of the first endpoint is received and adetermination is made that the current certificate differs from theprevious certificate. The current certificate is then provided to thedelivery manager for distribution to a plurality of other endpoints.

According to certain embodiments, the certificate comprises a keyidentifier, a public key, information about a version, and/or asignature.

According to certain embodiments, updated certificates are periodicallyrequested from the DNS or the delivery manager according to apre-determined time period.

According to certain embodiments, distributed file version managementtechnology is used to receive the certificate from the delivery manager.

Some embodiments of the disclosure may provide one or more technicaladvantages. A technical advantage of certain embodiments may beefficient management of a certificate within a network. For example, arecipient's certificate may be distributed to senders and stored inlocal memory associated with each sender. When a sender needs to send anencrypted message to the recipient, the sender can use the recipient'scertificate stored in local memory without having to ask a remoteresource, such as a central server or the recipient itself, for thecertificate. Thus, certain embodiments may reduce or eliminate latenciesand/or bandwidth penalties associated with having to ask a remoteresource for the certificate at the time the sender needs to send theencrypted message to the recipient. Additionally, storing certificatesin local memory may allow the sender to access and apply the certificateduring a temporary absence of the remote resource. In some embodiments,storing the certificate in local memory may reduce or eliminate raceconditions that would otherwise occur if a process was required toobtain the certificate from a remote resource (and therefore incurdelays) each time the certificate was needed.

An advantage of certain embodiments allows for obtaining certificatesfrom DNS. For example, in the event that members of a system do not haveany certificate for a recipient system or endpoint, the certificate canbe obtained from DNS without having to depend on the recipient system orendpoint to provide its certificate directly to the members of thesystem. In certain situations, this may allow the certificate to beobtained more quickly.

An advantage of certain embodiments allows for reducing certificatequeries to DNS. For example, a delivery manager may distribute thecertificate obtained from DNS to member systems so that each individualmember of the system need not send a query requesting the samecertificate from DNS.

An advantage of certain embodiments allows for periodically harvestingupdated certificates from DNS and distributing the updated certificatesto the member systems. This may help to ensure that member systems haveup-to-date certificates for recipient systems or endpoints in advance,which in turn may help to avoid latencies in the future when the membersystem needs to use the certificate to communicate with the recipientsystem or endpoint.

An advantage of certain embodiments allows for detecting a problem witha certificate obtained from DNS and notifying the owner of thecertificate of the problem.

An advantage of certain embodiments allows for inviting a recipientsystem or endpoint to become a member of a system in order to receive arepository of certificates associated with other systems or endpoints(which may help to avoid latencies in the future when the recipientsystem needs to use the certificate to communicate with the othersystems or endpoints).

An advantage of certain embodiments includes the ability to managevarious types of certificates, such as certificates used to encrypte-mail messages and/or certificates used to secure a connection (e.g.,TLS certificate). For simplicity, certain advantages have been describedwith respect to e-mail certificates. It will be understood by those ofordinary skill in the art that embodiments using other types ofcertificates may provide analogous advantages.

Some embodiments may benefit from some, none, or all of theseadvantages. Other technical advantages may be readily ascertained by oneof ordinary skill in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and itsfeatures and advantages, reference is now made to the followingdescription, taken in conjunction with the accompanying drawings, inwhich:

FIG. 1A illustrates an example of a system for distributing acertificate, according to certain embodiments;

FIG. 1B illustrates an example of a system for delivery of email,according to certain embodiments;

FIG. 2 illustrates an example of components of the system that mayfacilitate the distribution of certificates, according to certainembodiments;

FIG. 3 illustrates an example of components of the system that mayfacilitate obtaining a certificate from DNS, according to certainembodiments;

FIG. 4 illustrates an example of components of the system that mayfacilitate harvesting a certificate from DNS, according to certainembodiments;

FIG. 5 illustrates an example of elements that may be included in thecomponents described with respect to FIGS. 1-4, according to certainembodiments; and

FIGS. 6-13 illustrate examples of methods for distribution of acertificate, according to certain embodiments.

DETAILED DESCRIPTION

Embodiments of the present invention are described in FIGS. 1-13 of thedrawings, like numerals being used for like and corresponding parts ofthe various drawings.

In a computer network, a sender may transmit files, email messages, andother data to a recipient. The sender may encrypt the data to increasesecurity in some circumstances. As an example, the sender may encryptthe data using a public key encryption technique. In public keyencryption, two separate keys are associated with the recipient, apublic key and a corresponding private key. The sender Obtains therecipient's public key, encrypts the data using the public key, andtransmits the encrypted data to the recipient. The recipient decryptsthe encrypted data using its corresponding private key.

A recipient's public key can be communicated in a certificate. Forexample, the certificate may include information about the public key,information about the identity of the recipient, and the digitalsignature of an entity that has verified the certificate. To ensure thatthe sender has an up-to-date certificate, conventional systems mayrequire the sender to request the recipient's certificate from a remoteresource (e.g., a central storage facility or the recipient itself) eachtime the sender wishes to transmit data to the recipient. Requesting thecertificate from a remote resource introduces delay and consumesinternet access bandwidth. Additionally, the certificate may becometemporarily unavailable to the sender if the sender gets disconnectedfrom the remote resource. Embodiments of the present disclosure mayprovide solutions to these and other problems.

In some embodiments, a certificate associated with a recipient can bemade available (concurrently) to a broad population of message/contentsenders. Thus, encryption can be performed by each sender on amessage-by-message basis without per-message communication back to therecipient or a central storage facility.

In some embodiments, a central storage facility houses accuratereference copies of certificates for all recipients, network-wide. Fullcopies of the entire certificate store may then be conveyed to all ofthe senders (e.g., sending entities) in the network and maintained as‘local stored cache’ representations of the recipient certificates.After that, the central storage facility communicates recipientcertificates to the senders only occasionally as may be required to keepthe local copies current. For example, if an addition, deletion, ormodification is made to the reference copy of a recipient certificatestored in the central storage facility, the addition, deletion, ormodification may be communicated to the senders without having tocommunicate any unchanged recipient certificates. If each sendermaintains efficiently managed ‘local caches’ of all recipientcertificates needed to transmit data to any recipient on the network,the senders may be able to apply the recipient certificates to messageswhile conserving network bandwidth and resources associated withretrieving the certificates from a remote resource on a per-messagebasis.

In some embodiments, the recipient certificates may be stored in astandardized format at every location to enable off-the-shelfdistributed file version management technology to be used to keep filecopies aligned. In some embodiments, technology that is typically usedfor source file control in distributed software developmentenvironments, such as Git, J/Git, Subversion, Concurrent Versions System(CVS), or ClearCase, may be used as the distributed file versionmanagement technology.

In some embodiments, a delivery manager manages the distribution ofrecipient certificates to sending systems that are members of acertificate distribution network. In some embodiments, the deliverymanager obtains the recipient certificates from a domain name service(DNS). For example, a recipient system may publish its certificate toDNS, and the delivery manager may then obtain the recipient certificatefrom DNS (rather than having to request the certificate from therecipient system). The delivery manager can request/obtain the recipientcertificate directly from DNS, or the delivery manager can obtain therecipient certificate from DNS indirectly via one of themembers/sending, systems in the certificate distribution network. Thedelivery manager may then distribute the recipient certificates receiveddirectly or indirectly from DNS to the other sending systems. In certainembodiments, delivery manager can be configured to periodically harvestrecipient certificates from DNS. For example, if the delivery managerdetects that it does not have any DNS certificate for a particularrecipient system or if the delivery manager detects that the DNScertificate that it has for the recipient system is expired or otherwiseinvalid, delivery manager may request the certificate from DNS and maythen distribute the certificate to the sending systems.

FIG. 1A illustrates an example of a system 5 for distributing acertificate, according to certain embodiments. In the illustratedexample, system 5 includes a network 10 that communicatively couples aplurality of systems 20A-N, a delivery manager 30, a domain name service(DNS) 40, and a secure portal 50.

Systems 20A-N may comprise hardware and/or software and may be capableof both sending and receiving messages. Messages may include addressinformation and/or message information. Address information identifiesone or more intended recipients to which the message information isdirected. Examples of addresses include an email address, an IP address,a phone number, or other identifier associated with the intendedrecipient. Message information may include any content to becommunicated to the recipient. Examples of message information includedata such as a file, the body of an email, or content associated with aweb page, such as HTML content, XML instructions, etc, Messageinformation may include text, drawings, photographs, video, audio, etc.In some embodiments, a message may refer to an email.

For a given message, a particular system 20 may be configured as asending system or a recipient system. As an example, if system 20A wereto send a message to system 20B, system 20A would be considered thesending system and system 20B would be considered the recipient systemfor that message. In certain embodiments, sending system 20A may send amessage to recipient system 20B using a certificate associated withrecipient system 20B. Sending system 20A may obtain the certificate fromdelivery manager 30, as further discussed with respect to FIGS. 2-4below.

Each system 20 may include any suitable combination of hardware and/orsoftware, such as a computing system comprising one or more interfaces,logic, and/or one or more memories, which are described in more detailbelow. In some embodiments, system 20 may comprise a gateway thatmanages policy enforcement and/or content delivery on behalf of aplurality of devices associated with a company or other entity. Forexample, a company may maintain a network through which its employees orcustomers access company data using laptop computers, desktop computers,mobile phones, and/or other user devices. The gateway may manage policyenforcement and/or content delivery to the user devices that access thecompany's network. In alternative embodiments, certain policyenforcement may occur at the user device level and system 20 may referto the user device itself. In some embodiments, system 20 may include anemail application. System 20 may be operable to forward messages to auser device and/or to display messages on a display. System 20 maycommunicate with network 10 via a wired or wireless connection.

Each system 20 may optionally include support for encrypting messages,decrypting messages, and/or communicating messages using a secureconnection protocol (e.g., SSL, TLS). Prior to transmitting a message,sending system 20A may determine whether the message requiresencryption. The determination may be made based on whether a user hasrequested encryption or based on a pre-defined rule (such as a rule toencrypt messages to certain recipients, a rule to encrypt messages thatinclude certain keywords, etc).

If the message requires encryption, sending system 20A checks a localcache for one or more certificates associated with recipient system 20B.The local cache includes certificates previously obtained from deliverymanager 30, as further discussed with respect to FIGS. 2-4 below. If thelocal cache includes a certificate that is associated with recipientsystem 20B and corresponds to a desired encryption technique supportedby sending system 20A, sending system 20A encrypts the messageaccordingly. As an example, the desired encryption technique maycorrespond to the most secure technique supported by both sides or apreferred encryption technique indicated in a preference associated withrecipient system 20B. In some embodiments, the encryption technique maycorrespond to a public key encryption technique, such as S/MIME(Secure/Multipurpose Internet Mail Extensions), and sending system 20Amay determine recipient system 20B's public key from the certificate.Encryption may be applied at any suitable point in the sending path(e.g., by the sending user device or by the sending gateway). Similarly,decryption may be performed at any suitable point in the receiving path(e.g., by the receiving gateway or by the receiving user device).

If sending system 20A's local cache does not include recipient system20B's certificate for the desired encryption technique, sending system20A may optionally request the certificate from recipient system 20B inreal-time when sending the message to recipient system 20B. If sendingsystem 20A receives the certificate, sending system 20A may use thecertificate to send encrypted messages directly to the recipient system20B. Sending system 20A may also provide the certificate to deliverymanager 30 for distribution to other systems 20.

Alternatively, if sending system 20A's local cache does not includerecipient system 20B's certificate for the desired encryption technique,sending system 20A may optionally send the message to recipient system20B indirectly via secure portal 50. For example, secure portal 50 mayreceive message A encrypted according to a first technique supported bysending system 20A, decrypt message A, encrypt the message according toa second technique supported by recipient system 20B to yield message B,and communicate message B to recipient system 20B. In certainembodiments, sending messages via secure portal 50 prompts deliverymanager 30 to harvest recipient system 20B's certificate and distributeto systems 20.

In certain embodiments, delivery manager 30 may include one or moreservers. A server may refer to any suitable combination of hardwareand/or software implemented in one or more modules to process data andprovide the described functions and operations. In some embodiments, theserver may include, for example, a mainframe, host computer, datacenter, workstation, web server, file server, a personal computer suchas a laptop, or any other suitable device operable to process data. Insome embodiments, the server may execute any suitable operating systemsuch as IBM's zSeries/Operating System (z/OS), MS-DOS, PC-DOS, MAC-OS,WINDOWS, UNIX, OpenVMS, or any other appropriate operating systems,including future operating systems. In some embodiments, deliverymanager 30 may comprise a central storage facility that maintains anddistributes recipient certificates. In certain embodiments, deliverymanager 30 may refer to a distinct component external from systems 20.In other embodiments, functionality of delivery manager 30 could beincluded in one or more systems 20 (e.g., one system 20 may beconfigured to distribute certificates to other systems 20).

DNS 40 refers to a domain name service (or domain name system). Certainembodiments of DNS 40 have been specified in industry protocols and havebeen in use since approximately the 1980s. Thus, a person of ordinaryskill in the art would be familiar with conventional aspects of DNS 40.For example, in general, DNS 40 may encompass adistributed/decentralized naming system for computers, services, orother resources connected to the Internet or a private network. DNS 40associates various information with domain names assigned to each of theparticipating entities. As an example, DNS 40 may be configured totranslate domain names (such as ______.com, ______.org, ______.net, orother domain names) to numerical IP addresses needed for locating andidentifying computer services and devices with the underlying networkprotocols. As another example, DNS 40 may be configured to supportDNS-based authentication of named entities (DANE) protocol or otherprotocols in order to associate domain names with correspondingcertificates. For example, a first system may publish its certificate toDNS 40, and another system may request the first system's certificatefrom DNS 40 in order to be able to send encrypted messages to the firstsystem (e.g., the second system obtains the first system's public keyfrom the certificate received from DNS 40).

In certain embodiments secure portal 50 refers to a secure messagingportal, such as a ZixPort®. For example, in certain embodiments, sendingsystem 20A may send an encrypted message via secure portal 50. Secureportal 50 may decrypt the message and send a notification email torecipient system 20B that links to the message within secure portal 50.After a user of recipient system 20B signs in to an account that secureportal 50 associates with the user (such as a webmail account providedby secure portal 50), the user can view the linked message and anyattachments over a secure connection, such as Hypertext TransferProtocol Secure (HTTPS), Secure Socket Layer (SSL), Transport LayerSecurity (TLS), or other secure connection.

Communication network 10 may comprise any one or more interconnectingnetworks for communicatively coupling components of system 5. Forexample, communication network 10 may comprise all or a portion of oneor more of the following: a public snitched telephone network (PSTN), apublic or private data network, a local area network (LAN), ametropolitan area network (MAN), a wide area network (WAN), a local,regional, or global communication or computer network such as theInternet, a wireline or wireless network, an enterprise intranet, othersuitable communication link, or any combination of any of the preceding.

FIG. 1B illustrates an example of a system for delivery of email, inaccordance with certain embodiments. The system may include one or moremail applications 22, secure mail applications 24, mail delivery servers26, and/or gateways 28. Depending on the embodiment, any of mailapplications 22, secure mail applications 24, mail delivery servers 26,and/or gateways 28 may perform some or all of the operations describedwith respect to system 20 (e.g., sending system 20A or recipient system20B) of FIG. 1A.

Mail application 22 may refer to an application through which a useraccesses the user's mailbox in order to compose outbound entails, viewinbound emails, and so on. Mail application 22 may run on a user device,such as a laptop computer, desktop computer, mobile phone, etc, Examplesof mail application 22 include. Microsoft Outlook®, Lotus Notes®, GoogleGmail®, and so on. Secure mail application 24 may be similar to mailapplication 22 and may include additional security functionality. Forexample, secure mail application may be able to encrypt and decryptemail. In some embodiments, a secure mail plug-in may be used to add thesecurity functionality to a mail application 22 in order to yield securemail application 24. Mail applications 22 and 24 may be associated witha mail delivery server 26 and/or gateway 28 (e.g., as shown by mailapplications 22 a, 24 a, 22 b, 22 c, and 24 b of FIG. 1B) or may bestandalone (e.g., as shown by mail applications 22 d and 24 c of FIG.1B).

Mail delivery server 26 may refer to a server that delivers email to theuser's mailbox. As an example, a Microsoft Exchange® server. In someembodiments, mail delivery server 26 may correspond to a particulardomain. For example, mail delivery server 26 a may correspond to CompanyA and may deliver entails to and from the domain @CompanyA.com. Asillustrated, mail application 22 a may correspond to a user within thedomain, such as User_1@CompanyA.com, and secure mail application 24 amay correspond to another user within the domain, such asUser_2@CompanyA.com. Thus, mail delivery server 26 a delivers emailsto/from User_1@CompanyA.com and emails to/from User_2@CompanyA.com. Maildelivery server 26 b may deliver entails within a different domain, suchas @CompanyB.com, and may deliver emails to and from mail applicationsassociated with Company B (e.g., as shown in by mail applications 22 band 22 c, and secure mail application 24 b of FIG. 1B).

Gateway 28 may refer to a mail relay positioned between a privatenetwork (such as Company A's network) and an outside network (such asthe Internet or Company B's network). In some embodiments, gateway 28may be positioned at the edge of the private network. As an example,gateway 28 a may receive email from mail delivery server 26 a, applypolicies for sending email to the outside network, and then forward theemail to the outside network (e.g., via network 10). Similarly, gateway28 a may receive email from the outside network (e.g., via network 10),apply policies for receiving email from the outside network, and thenforward the email to mail delivery server 26 a for delivery to theappropriate mailbox. In some embodiments, redundant gateways may be usedto provide load balancing, disaster recovery, or other redundancy. Forexample, gateway 28 a′ may operate as a redundant gateway for gateway 28a. Gateway 28 a and redundant gateway 28 a′ may each maintain localcopies of current certificates so that either gateway is prepared toprocess email.

Mail applications 22, secure mail applications 24, mail delivery servers26, and gateways 28 may communicate using a shared protocol, such asSimple Mail Transfer Protocol (SMTP). Using the same protocol may allowfor sending the email along any suitable path between any suitablesender and recipient. For example, sending mail application 22 (or 24)may send an email directly to a receiving mail application 22 (or 24),directly to a receiving gateway 28 that facilitates delivery of theemail to the receiving mail application 22 (or 24), or to secure portal50 to facilitate delivery of the email to the receiving mail application22 (or 24) either directly or via a receiving gateway 28. In thepreceding example, sending mail application 22 (or 24) may send theoutbound email via a sending gateway 28 (e.g., mail application 22 asends email via sending gateway 28 a) or independently of a gateway(e.g., mail application 22 d sends email directly to the receivingcomponent, wherein the receiving component could be receiving mailapplication 22 itself or an intermediate receiving component, such as agateway 28 associated with receiving mail application 22 or secureportal 50).

In some embodiments, the method of entail delivery may depend oncertificate availability. As an example, if gateway 28 a possesses acertificate for gateway 28 b, a policy may instruct gateway 28 a to sendemail directly to gateway 28 b. But, if gateway 28 a does not possess acertificate for gateway 28 b, the policy may instruct gateway 28 a tosend email to gateway 28 b indirectly via secure portal 50.

Certificates may be distributed to and applied at any suitable point inthe email transmission. As an example, certificates may be applied bysecure mail application 22, gateway 28, or secure portal 50. FIGS. 2-4below describe systems and methods for distributing certificates to asystem 20, such as gateway 28 or secure mail application 24.

FIG. 2 illustrates an example of components 200 that may facilitate thedistribution of certificates within system 5. In the illustratedexample, systems 20 each comprise a gateway manager 210 and a preferencerepository 260, and delivery manager 30 comprises preference server 220,update module 230, download module 240, and load balancer 250.Components 200 may be used to provide one or more preferences ofrecipient system 20B to sending system 20A.

Recipient preferences indicate how recipient system 20B prefers messagesto be delivered to recipient system 20B. As an example, a preference mayinclude one or more certificates associated with recipient system 20B.The certificate may include various attributes, such as a keyidentifier, a public key, version information, and a signature. Deliverymanager 30 may distribute the certificate to each system 20 on thenetwork so that systems 20 sending messages to recipient system 20B canencrypt the data in a manner that recipient system 20E will be able todecrypt using its corresponding private key. S/MIME or any othersuitable encryption protocol may be used by systems 20.

To provide sending system 20A with preferences, delivery manager 30 mustfirst receive preferences of recipient system 20B. In the exampleembodiment of FIG. 2, preference server 220 of delivery manager 30 mayreceive preferences from gateway manager 210 b residing on recipientsystem 20B. FIGS. 3 and 4, discussed below, illustrate additionalmethods that can be used by delivery manager 30 to obtain preferences(e.g., certificates) associated with recipient system 20B. Deliverymanager 30 may be configured to perform one or more of the techniques ofFIGS. 2, 3, and/or 4 in order to obtain the preferences of recipientsystem 20B.

In some embodiments, preference server 220 comprises an interface toreceive preferences recipient system 20B. System 20B may communicatecurrent, up-to-date preferences to preference server 220 in response toan operation that causes preferences to change, such as an add, modify,or remove operation. Logic in preference server 220 may process add,modify, and remove operations and may store current preferences in apreference server database (e.g., a DB2 database) associated withpreference server 220.

Preference server 220 may interface with update module 230 residing indelivery manager 30 (e.g., a data center). Update module 230 maycomprise an update service 232, a clone reference repository 234, and amaster reference repository 236. Update service 232 may receive currentpreferences from preference server 220 and may interact with clonereference repository 234 and master reference repository 236 tofacilitate distributing preferences to systems 20.

In some embodiments, update service 232 may comprise a Java-based webapplication running inside a Tomcat Servlet container with Apache.Update service 232 may use a distributed file version managementtechnology, such as Git, J/Git, Subversion, Concurrent Versions System(CVS), or ClearCase, to manage the version of the preference (e.g.,certificate or other preference) that gets distributed to and stored inthe various repositories of delivery manager 30 and systems 20.

Initially, update service 232 may create clone reference repository 234comprising a file structure representation of preferences located in thepreference server database (e.g., a DB2 database associated withpreference server 220). Once clone reference repository 234 has beencreated, it may be copied as master reference repository 236 and thendownloaded to systems 20 as discussed in more detail below. Referencerepositories 234 and 236 may be formatted according to a standardizedformat used by the file version management technology implemented in thesystem. As an example, reference repositories 234 and 236 may be Gitrepositories in systems implementing Git file version managementtechnology.

After creating the initial reference repositories 234 and 236, updateservice 232 may periodically update the reference repositories 234 and236. For example, update service 232 may periodically poll preferenceserver 220 to obtain all active preferences including currentpreferences (including current certificates) associated with recipientsystem 20B. Polling may occur at a configurable, pre-determined timeinterval, such as once every 1 minute, every 2 minutes, every 5 minutes,every 10 minutes, or other suitable time interval. Update service 232generates clone reference repository 234 by copying master referencerepository 236 into a working copy that can be edited by update service232. The working copy includes previous preferences includingpreferences that have been previously distributed to systems 20. Updateservice 232 compares each of the active preferences to the previouspreferences to determine differences. For example, update service 232may determine that recipient system 20B's current preferences aremissing from clone reference repository 234. Update service 232 thenupdates clone reference repository 234 by adding current preferencesassociated with recipient system 20B.

As discussed above, the current preferences may include one or morecertificates associated with recipient system 20B. Update service 232may validate the signature of the certificate. If the certificate doesnot pass validation, the certificate will not be part of the set ofcertificates that are analyzed to update clone reference repository 234.If the certificate passes validation, update service 232 may compare thehash of the certificate in current preferences to the hash of acorresponding certificate in previous preferences stored in clonereference repository 234. If the hash values are the same, no actionwill be taken because clone reference repository 234 already has anup-to-date certificate. If the hash values are different, update service232 will replace the previous certificate with the current certificate.If the certificate does not exist in clone reference repository 234,update service 232 will add it. If clone reference repository 234contains certificates that are not in the preference server database,update service 232 will delete them from clone reference repository 234.

After update service 232 has made all of the changes to clone referencerepository 234, update service 232 may create a commit and signature tagthat can eventually be checked by systems 20 to ensure changes topreferences going to systems 20 have not been tampered with. Updateservice 232 then communicates/copies clone reference repository 234 tomaster reference repository 236 so that master reference repository 236has the current state of preferences for the entire system. Either apull method or, in the alternative, a push method may be used tocommunicate clone reference repository 234.

Download module 240 facilitates downloading changes from update module230 to sending system 20A and other systems 20 configured to receivepreferences from delivery manager 30. For example, download module 240may pull changes contained in master reference repository 236 into aslave reference repository 242 so that slave reference repository 242becomes a mirror image of master reference repository 236. The changesmay include the additions/modifications according to currentpreferences. Download module 240 may pull the changes (without having topull unchanged data) at a configurable, pre-determined time interval,such as once every 1 minute, every 2 minutes, every 5 minutes, every 10minutes, or other suitable time interval.

Download module 240 accepts and authenticates requests from systems 20to update the preferences. For example, a system 20 may download andstore preferences in a preference repository 260 residing in localmemory of system 20. In some embodiments, download module 240 maycomprise a Java-based web application running in delivery manager 30(e.g., a data center) that utilizes a distributed file versionmanagement technology, such as Git, J/Git, Subversion, ConcurrentVersions System (CVS), or ClearCase, to manage the version of thepreference that gets distributed to and stored in preference repository260 of sending system 20A. The web application may run inside a TomcatServlet container with Apache, Download module 240 may be associatedwith a Uniform Resource Locator (URL) that systems 20 access using aHypertext Transfer Protocol Secure (HTTPS) call. In some embodiments,the HTTPS call will be received by a load balancer 250 between sendingsystem 20A and download module 240. The load balancer 250 may provideload distribution and disaster recovery. Sending system 20A may calldownload module 240 at a configurable, pre-determined time interval,such as once every 1 minute, every 2 minutes, every 5 minutes, every 10minutes, or other suitable time interval.

Sending system 20A calls download module 240 to retrieve currentpreference and any other changes from slave reference repository 242(e.g., a repository formatted according to a standardized format thatcorresponds to the file version management technology implemented in thesystem, such as a Git respository, J/Git repository, Subversionrepository, Concurrent Versions System (CVS) repository, or ClearCaserepository). As discussed above, in some embodiments, preferences mayinclude one or more certificates that recipient system 20B would likesending system 20A to use when sending messages 105 to recipient system20B. In some embodiments, sending system 20A may download currentpreferences to public bare repository 262. Sending system 20A may usepublic bare repository 262 to update preferences and to validate thesignature tag before committing the changes. Once the updates andvalidation are complete, public bare repository 262 may be copied (e.g.,using a push or pull method) to public clone repository 264. Sendingsystem 20A may access public clone repository 264 to obtain preferencesin the future when it needs to send a message to recipient system 20B.Thus, preferences may be available to sending system 20A in advance. Asa result, sending system 20A can apply per message preferences withouthaving to wait until the time it begins processing the message to getthe preferences from delivery manager 30 (or another remote resource).

In some embodiments, sending system 20A can have a sending policyindicating how to apply recipient preferences. For example, even ifsending system 20A and recipient system 20B support encryption, thepolicy may instruct sending system 20A not to perform encryption incertain circumstances. As sending system 20A processes a new message,sending system 20A may apply the policy that determines whether or notto encrypt the data. The policy may define encryption decisions based onthe identity of the recipient, the sensitivity of the message, or othercriteria.

Although the preceding example describes distributing public keys from asending system 20A to a recipient system 20B, analogous methods may beused to distribute preferences between any suitable components of system5. As an example, file version management technology may be used withina private network to distribute private keys or other local preferencesfrom a managing gateway 28 a to a redundant gateway 28 a′. The redundantgateway 28 a′ may be located within the same private network and mayprovide load balancing, disaster recovery, or other redundancyfunctionality for the managing gateway 28 a. Gateway manager 210 aassociated with managing gateway 28 a may use file version managementtechnology to distribute a private key to private clone repository 266associated with redundant gateway 28 a′. When the gateway manager 210 aadds/deletes/modifies private clone repository 266, the changes can becommitted to private bare repository 268. In some embodiments, changescan be made to private clone repository 266 without having to validate asignature. This is because the private key originates from and ismaintained within the private network and is therefore less likely tohave been tampered with. The redundant gateway 28 a′ may then retrievethe up-to-date private keys from private clone repository 266, forexample, when it needs to decrypt messages.

FIG. 3 illustrates an example of components of the system that mayfacilitate obtaining a certificate from DNS, according to certainembodiments. FIG. 3 illustrates a system 20, delivery manager 30, andDNS 40 similar to those described above with respect to FIGS. 1-2. Incertain embodiments, system 20 may comprise a gateway or mail relay, anddelivery manager 30 may comprise a data center. In FIG. 3, system 20includes an encryption engine 320, a certificate cache 322 comprising aplurality of certificates (smime/A, smime/B, . . . smime/N), and acertificate download utility 324. Delivery manager 30 includes acertificate server 330, a certificate cache clone 332, and a certificatedownload utility 334.

Encryption engine 320 performs encryption functionality for system 20.For example, encryption engine 320 may receive an inbound message andmay decrypt the inbound message based on a private key that encryptionengine 320 maintains for system 20. As another example, encryptionengine 320 may encrypt an outbound message using a public key of therecipient system to which the outbound message is addressed. To encryptthe outbound message, encryption engine 320 checks certificate cache 322to determine whether system 20 has a certificate for recipient system.If so, encryption engine 320 may further check whether the certificateis valid and supports a desired encryption technique (e.g., based onsecurity requirements of the outbound message). If encryption engine 320determines that certificate cache 322 needs a certificate associatedwith the recipient system, encryption engine 320 may request thecertificate from DNS 40. For example, in some embodiments, encryptionengine 320 uses DANE protocol to request the certificate from DNS 40.

If DNS 40 has the requested certificate, DNS 40 provides a copy of thecertificate to system 20. For purposes of example, suppose the requestedcertificate comprises “smime/X.” After obtaining smime/X from DNS 40,encryption engine 320 uses smime/X to encrypt the outbound message andthen sends the encrypted message for delivery to the recipient system.Encryption engine 320 also stores smime/X in certificate cache 322 andprovides a copy of smime/X to delivery manager 30's certificate server330.

Delivery manager 30's certificate server 330 adds the smime/X tocertificate cache clone 332. Thus, smime/X becomes available to bedistributed to other systems 20 via the certificate download utility334. For example, in some embodiments, certificate download utility 334may comprise a Java-based web application running inside a TomcatServlet container with Apache. Certificate download utility 334 may usea distributed file version management technology, such as Git, J/Git,Subversion, Concurrent Versions System (CVS), or ClearCase, to managethe version of the certificate that gets distributed to and stored inthe various repositories of delivery manager 30 and systems 20.

In FIG. 3, system 20's certificate download utility 324 receivescertificates from delivery manager 30's certificate download utility 334and stores the certificates in certificate cache 322. In the example,the particular system 20 that already obtained smime/X from DNS 40,would not need to obtain smime/X from delivery manager 30. However,system 20 may obtain other certificates from delivery manager 30 (suchas certificates that delivery manager 30 harvests from DNS 40 orreceives from other systems 20).

FIG. 4 illustrates an example of components of the system that mayfacilitate harvesting a certificate from DNS, according to certainembodiments. FIG. 4 illustrates a system 20, delivery manager 30, andDNS 40 similar to those described above with respect to FIGS. 1-3. Incertain embodiments, system 20 may comprise a gateway or mail relay, anddelivery manager 30 may comprise a data center. In FIG. 4, system 20includes a certificate cache 322 comprising a plurality of certificates(smime/A, smime/B, . . . smime/N) and a certificate download utility324. Delivery manager 30 includes a certificate server 330, reportingdata 344, certificate repository updater 350, and certificate downloadutility 334.

Certificate server 330 comprises a certificate database 340 and acertificate harvester 342. Certificate harvester 342 harvestscertificates from DNS 40. In certain embodiments, certificate harvester342 harvests certificates based on analyzing reporting data 344. Forexample, reporting data 344 may comprise logs, reports, statistics, etc.collected to monitor the performance of systems 20. Certain logs may begenerated if system 20 sends a message, receives a message, sets up atransport layer connection, etc. Certificate harvester 342 mayperiodically review the data to determine whether it includes any errorsor other information indicating to harvest a certificate from DNS 40.For example, if reporting data 344 indicates that a system 20 could notsend an encrypted message to a recipient X (e.g., if reporting data 344indicates that the message to recipient X was sent in plaintext or viasecure portal 50), certificate harvester 342 determines to harvest thatrecipient X's certificate from DNS 40.

As another example, in certain embodiments, certificate harvester 342determines to harvest certificates based on reviewing information fromcertificate database 340. For example, if certificate harvester 342determines that a certificate that certificate database 340 maintainsfor recipient X is invalid, expired (or a about to expire), certificateharvester 342 may harvest a current/valid/updated certificate from DNS40. Certificate harvester 342 may initiate harvesting certificates forany other suitable reason.

To harvest certificates, certificate harvester 342 sends a request toDNS 40. For example, in certain embodiments, certificate harvester 342may use DANE protocol to request the certificate. Certificate harvester342 may send requests on an as-needed basis or on a periodic basis. Forexample, certificate harvester 342 may periodically request batches ofcertificates to be updated. If DNS 40 has the requested certificate(s),DNS 40 provides the certificate(s) to certificate harvester 342.

Certificate harvester writes the certificates received from DNS 40 tocertificate database 340 of certificate server 330. Certificaterepository updater 350 may then obtain the certificates from certificatedatabase 340. For example, certificate update service 352 withincertificate repository updater 350 may receive current certificates fromcertificate server 330 and may interact with clone certificate cacherepository 354 and master certificate cache repository 356 to facilitatedistributing certificates to systems 20.

In some embodiments, certificate update service 352 may comprise aJava-based web application running inside a Tomcat Servlet containerwith Apache. Certificate update service 352 may use a distributed fileversion management technology, such as Git, J/Git, Subversion,Concurrent Versions System (CVS), or ClearCase, to manage the version ofthe certificate that gets distributed to and stored in the variousrepositories of delivery manager 30 and systems 20.

Initially, certificate update service 352 may create clone certificatecache repository 354 comprising a file structure representation ofcertificates located in certificate database 340 (e.g., a DB2 databaseassociated with certificate server 330). Once clone certificate cacherepository 354 has been created, it may be copied as master certificatecache repository 356 and then downloaded to systems 20. Repositories 354and 356 may be formatted according to a standardized format used by thefile version management technology implemented in the system. As anexample, repositories 354 and 356 may be Git repositories in systemsimplementing Git file version management technology.

After creating the initial certificate repositories 354 and 356,certificate update service 352 may periodically update the repositories354 and 356. For example, certificate update service 352 mayperiodically poll certificate server 330 to obtain all activecertificates including current certificates. Polling may occur at aconfigurable, pre-determined time interval, such as once every 1 minute,every 2 minutes, every 5 minutes, every 10 minutes, or other suitabletime interval. Certificate update service 352 generates clonecertificate cache repository 354 by copying master certificate cacherepository 356 into a working copy that can be edited by certificateupdate service 352. The working copy includes previous certificatesincluding certificates that have been previously distributed to systems20. Certificate update service 352 compares each of the activecertificates to the previous certificates to determine differences. Forexample, certificate update services 352 may determine that recipientsystem. 20B's current certificates are missing from clone certificatecache repository 354. Certificate update service 352 then updates clonecertificate cache repository 354 by adding current certificatesassociated with recipient system 20B.

Certificate update service 352 may validate the signature of thecertificate. If the certificate does not pass validation, thecertificate will not be part of the set of certificates that areanalyzed to update done certificate cache repository 354. If thecertificate passes validation, certificate update service 352 maycompare the hash of the current certificate to the hash of acorresponding previous certificate stored in done certificate cacherepository 354. If the hash values are the same, no action will be takenbecause clone certificate cache repository 354 already has an up-to-datecertificate, if the hash values are different, certificate updateservice 352 will replace the previous certificate with the currentcertificate. If the certificate does not exist in clone certificatecache repository 354, certificate update service 352 will add it. Ifdone certificate cache repository 354 contains certificates that are notin the certificate database 340 (e.g., because the certificates haveexpired or become certificate update service 352 will delete them fromclone certificate cache repository 354.

After certificate update service 352 has made all of the changes toclone certificate cache repository 354, certificate update service 352may create a commit and signature tag that can eventually be checked bysystems 20 to ensure changes to certificates going to systems 20 havenot been tampered with. Certificate update service 352 thencommunicates/copies clone certificate cache repository 354 to mastercertificate cache repository 356 so that master certificate cacherepository 356 has the current state of certificates for the entiresystem. Either a pull method or, in the alternative, a push method maybe used to communicate clone certificate cache repository 354.

Download module 334 facilitates downloading changes to systems 20configured to receive certificates from delivery manager 30. Forexample, download module 334 may pull changes contained in mastercertificate cache done repository 356 into a slave repository 332 sothat slave repository 332 becomes a mirror image of master certificatecache repository 356. The changes may include the added/updatedcertificates. Download module 334 may pull the changes (without havingto pull unchanged data) at a configurable, pre-determined time interval,such as once every 1 minute, every 2 minutes, every 5 minutes, every 10minutes, or other suitable time interval.

Download module 334 accepts and authenticates requests from systems 20to update the certificates. For example, a system 20 may download andstore certificates to certificate cache 322 residing in local memory ofsystem 20. In some embodiments, download module 334 may comprise aJava-based web application running in delivery manager 30 (e.g., a datacenter) that utilizes a distributed file version management technology,such as Git, J/Git, Subversion, Concurrent Versions System (CVS), orClearCase, to manage the version of the certificate that getsdistributed to and stored in certificate cache 322 of sending system20A. The web application may run inside a Tomcat Servlet container withApache. Download module 334 may be associated with a Uniform ResourceLocator (URL) that systems 20 access using a Hypertext Transfer ProtocolSecure (HTTPS) call. In some embodiments, the HTTPS call will bereceived by a load balancer between sending system 20A and downloadmodule 334. The load balancer may provide load distribution and disasterrecovery. Sending system 20A may call download module 334 at aconfigurable, pre-determined time interval, such as once every 1 minute,every 2 minutes, every 5 minutes, every 10 minutes, or other suitabletime interval.

Sending system 20A may include a certificate download utility 324configured to call download module 334 to retrieve current certificatesfrom slave repository 332 (e.g., a repository formatted according to astandardized format that corresponds to the file version managementtechnology implemented in the system, such as a Git repository, J/Gitrepository, Subversion repository, Concurrent Versions System (CVS)repository, or ClearCase repository). Once sending system 20A completesthe updating and validation of the certificates, sending, system 20A mayaccess certificate cache 322 to obtain certificates in the future whenit needs to send a message to (or establish a transport layer connectionwith) recipient system 20B. Thus, certificates may be available tosending system 20A in advance. As a result, sending system 20A can applyper message certificates without having to wait until the time it beginsprocessing, the message to get the certificates from delivery manager 30(or another remote resource).

FIG. 5 illustrates an example of elements 500 that may be included inthe systems and apparatuses disclosed herein. For example, any ofnetwork 10, systems 20, delivery manager 30, DNS 40, and/or secureportal 50 may include one or more interface(s) 510, processing circuitry520, memory(ies) 530, and/or other suitable element(s), interface 510receives input, sends output, processes the input and/or output, and/orperforms other suitable operation. Interface 510 may comprise hardwareand/or software.

Processing circuitry 520 performs or manages the operations of thecomponent. Processing circuitry 520 may include hardware and/orsoftware. Examples of a processing circuitry include one or morecomputers, one or more microprocessors, one or more applications, etc.In certain embodiments, processing circuitry 520 executes logic (e.g.,instructions) to perform actions (e.g., operations), such as generatingoutput from input. The logic executed by processing circuitry 520 may beencoded in one or more tangible, non-transitory computer readable media(such as memory 530). For example, the logic may comprise a computerprogram, software, computer executable instructions, and/or instructionscapable of being executed by a computer. In particular embodiments, theoperations of the embodiments may be performed by one or more computerreadable media storing, embodied with, and/or encoded with a computerprogram and/or having a stored and/or an encoded computer program.

Memory 530 (or memory unit) stores information. Memory 530 may compriseone or more non-transitory, tangible, computer-readable, and/orcomputer-executable storage media. Examples of memory 530 includecomputer memory (for example, Random Access Memory (RAM) or Read OnlyMemory (ROM)), mass storage media (for example, a hard disk), removablestorage media (for example, a Compact Disk (CD) or a Digital Video Disk(DVD)), database and/or network storage (for example, a server), and/orother computer-readable medium.

FIG. 6 illustrates an example of a method for distribution of acertificate, according to certain embodiments. The method begins at step602 where a recipient system 20B publishes its certificate (e.g., SMIMEcertificate) with DNS 40. As an example, recipient system 20B may useDANE protocol to publish its certificate with DNS 40. Recipient system20B may determine to publish its certificate with DNS 40 in order toenable DNS 40 to provide the certificate to other systems 20 in responseto future requests for the certificate.

At step 604, sending system 20A prepares a message to be sent torecipient system 20B, and at step 606 sending system 20A determines thatrecipient system 20B's certificate is needed to send the message. Forexample, sending system 20A determines that the certificate is needed ifthe message requires encryption and sending system 20A does not have acopy of recipient system 20B's certificate stored in local memory.

At step 608, sending system 20A requests recipient system 20B'scertificate from DNS 40. The request uses recipient system 20B's DNSname to identify the certificate being requested. Examples of DNS namesinclude domain names, fully qualified domain names, machine names, etc.In certain embodiments, the DNS name corresponds to an individual mailclient, such as a user mail client with s/mime managed by a desktopemail client. For example, the DNS name may be an email address of theuser. In certain embodiments, the DNS name corresponds to a mailtransfer agent. A mail transfer agent refers to an agent that handlesemail for an email domain. Examples of a mail transfer agent include amail gateway or mail relay. In certain embodiments, the request may beconfigured according to DANE protocol.

At step 610, sending system 20A receives the certificate that DNS 40associates with the DNS name of recipient system 20B. Sending system 20Aobtains recipient system 20B's certificate from DNS 40 in real-time whensending the message to recipient system 20B for which sending system 20Adoes not have the certificate.

At step 612, sending system 20A uses recipient system 20B's certificate(i.e., the certificate received from DNS 40 in step 610) to encrypt themessage, and at step 614 sending system 20A sends the encrypted messageto recipient system 20B.

At step 616, sending system 20A provides recipient system 20B'scertificate to delivery manager 30 for distribution to the other sendingsystems, such as sending system 20N. That is, in the embodiment of FIG.6, delivery manager 30 receives the certificate that DNS 40 associateswith the DNS name of recipient system 20B via sending system 20A.

At step 618, delivery manager 30 distributes recipient system 20B'scertificate to a plurality of sending systems 20. In certainembodiments, the certificate is distributed to the sending systems usingdistributed file version management technology. In certain embodiments,the certificate is distributed to the plurality of sending systemsaccording to a pre-determined time period. For example, delivery manager30 may send updates to the sending systems at regular intervals based onthe pre-determined time period. Alternatively, delivery manager 30 maysend updates to the sending systems as delivery manager 30 receivesnew/updated certificates, without having to wait for the pre-determinedtime period. In certain embodiments, the certificate is made availableto the plurality of sending systems concurrently.

In the illustration, the plurality of sending systems 20 include sendingsystem 20N. Each sending system 20, such as sending system 20N, isconfigured to store recipient system 20B's certificate in its localmemory (step 620), in response to a future determination to send anencrypted message to recipient system 20B (step 622) use recipientsystem 20B's certificate from local memory to perform encryption (step624), and send the encrypted message directly to recipient system 20B(step 626).

FIG. 7 illustrates another example of a method for distribution of acertificate, according to certain embodiments. The method begins at step702 where a recipient system 20B publishes its certificate with DNS 40.As an example, recipient system 20B may use DANE protocol to publish itscertificate with DNS 40. Recipient system 20B may determine to publishits certificate with DNS 40 in order to enable DNS 40 to provide thecertificate to other systems 20 in response to future requests for thecertificate.

At step 704, delivery manager 30 sends a request message to DNS 40. Therequest message requests the certificate associated with the DNS name ofrecipient system 20B. The DNS name of recipient system 20B maycorrespond to an individual mail client or a mail transfer agent. Incertain embodiments, delivery manager 30 sends the request message aspart of a discovery procedure, as further discussed below with respectto FIG. 8. In certain embodiments, delivery manager 30 sends the requestmessage in response to determining that the certificate is needed by asending system 20, for example, as further discussed below with respectto FIG. 9. In certain embodiments, the request is sent according to DANEprotocol.

At step 706, delivery manager 30 receives the certificate that DNS 40associates with the DNS name of recipient system 20B. In the example ofFIG. 7, the certificate is received from DNS 40 as a result of sendingthe request message in step 704.

At step 708 a-n, delivery manager 30 distributes recipient system 20B'scertificate to a plurality of sending systems, such as sending systems20A and 20N. In certain embodiments, the certificate is distributed tothe sending systems using distributed file version managementtechnology. In certain embodiments, the certificate is distributed tothe plurality of sending systems according to a pre-determined timeperiod. For example, delivery manager 30 may send updates to the sendingsystems at regular intervals based on the pre-determined time period.Alternatively, delivery manager 30 may send updates to the sendingsystems as delivery manager 30 receives new/updated certificates,without having to wait for the pre-determined time period. In certainembodiments, the certificate is made available to the plurality ofsending systems concurrently.

Each sending system 20 is configured to store the certificate in localmemory of the sending system (e.g., sending systems 20A and 20N storethe certificate in steps 710 and 712, respectively), in response to afuture determination to send an encrypted message to the recipientsystem (e.g., sending system 20A prepares a message in step 714), usethe certificate from the local memory of the sending system to performencryption (e.g., sending system 20A encrypts the message in step 716),and send the encrypted message directly to recipient system 20B (e.g.,sending system 20A sends the message in step 718).

FIG. 8 illustrates another example of a method for distribution of acertificate, according to certain embodiments. In certain embodiments,the method may be performed by delivery manager 30. At step 802,delivery manager 30 initiates a discovery procedure in order to discoverwhether DNS 40 has a certificate (or an updated certificate) associatedwith recipient system 20B. As part of the discovery procedure, deliverymanager 30 sends a request message to DNS 40 at step 804. The requestmessage requests the certificate associated with the DNS name of therecipient system (e.g., similar to step 704 of FIG. 7). The discoveryprocedure can be initiated and the request message sent withoutrequiring recipient system 20B (or the owner of recipient system 20B'sDNS name) to inform delivery manager 30 that the certificate exists. Forexample, delivery manager 30 may automatically check whether DNS 40 hasthe certificate based on determining that one or more sending systems 20have sent (or attempted to send) messages to recipient system 20B.

If DNS 40 has a certificate for recipient system 20B, DNS 40 providesthe certificate in response to receiving the request message fromdelivery manager 30. At step 806, delivery manager 30 receives thecertificate that DNS 40 associates with the DNS name of a recipientsystem (e.g., similar to step 706 of FIG. 7). At step 808, deliverymanger 30 distributes the certificate to a plurality of sending systems20 (e.g., similar to steps 708 a-n in FIG. 7). Sending systems 20 maythen store the certificate in local memory for future use.

FIG. 9 illustrates another example of a method for distribution of acertificate, according to certain embodiments. In certain embodiments,the method may be performed by delivery manager 30. At step 902,delivery manger 30 determines that sending system 20A failed to send theencrypted message directly to recipient system 20B. In certainembodiments, the determination that sending system 20A failed to sendthe encrypted message directly to recipient system 20B is made based ondata reported from sending system 20A. The data may comprise anotification from sending system 20 that it failed to encrypt themessage. Alternatively, the data may comprise information from whichdelivery manager 30 can determine that sending system 20A failed toencrypt the message. As an example, if delivery manager 30 receives dataindicating that the message from sending system 20A to recipient system20B was sent in plain text (i.e., unencrypted) or was sent indirectlyvia secure portal 50, delivery manager 30 infers that sending system 20Afailed to send the encrypted message directly to recipient system 20B.

At step 904, in response to determining that sending system 20A failedto send the encrypted message directly to recipient system 20B, deliverymanager 30 sends a request message to DNS 40. The request messagerequests the certificate associated with the DNS name of recipientsystem 20B (e.g., similar to step 704 of FIG. 7). In certainembodiments, sending the request of step 904 is part of a harvestingprocedure in which delivery manager 30 periodically reviews datareported from the plurality of sending systems 20 according to aconfigured periodicity (such as every 5 minutes, 1 hour, 1 day, 1 week,or other suitable periodicity), determines each instance in which anyone of the sending systems 20 failed to send an encrypted messagedirectly to any one of the recipient systems 20, and if delivery manager30 does not already have the certificates of the recipient system 20available to distribute, harvests the certificates from DNS 40 (e.g., bysending the request message of step 904).

If DNS 40 has a certificate for recipient system 20B, DNS 40 providesthe certificate in response to receiving the request message fromdelivery manager 30. At step 906, delivery manager 30 receives thecertificate that DNS 40 associates with the DNS name of a recipientsystem (e.g., similar to step 706 of FIG. 7). At step 908, deliverymanger 30 distributes the certificate to a plurality of sending systems20 (e.g., similar to steps 708 a-n in FIG. 7). Sending systems 20 maythen store the certificate in local memory for future use.

Although the method of FIG. 9 has been described as being performed bydelivery manager 30, in other embodiments, the method of FIG. 9 could beperformed by the sending system 20A itself. For example, if sendingsystem 20A determines that it is unable to send an encrypted messagedirectly to recipient system 20B, sending system 20A may request thecertificate from DNS 40, obtain the certificate from DNS 40, and providethe certificate to delivery manger 30 for distribution to other sendingsystems.

FIG. 10 illustrates another example of a method for distribution of acertificate, according to certain embodiments. In certain embodiments,the method may be performed by delivery manager 30. At step 1002,delivery manger 30 sends an invitation message to recipient system 20B.In certain embodiments, the invitation is considered to have been sentto recipient system 20B if the invitation is directed to the owner ofthe DNS name associated with recipient systems 20B. The invitationmessage invites recipient system 20B to become a member of the pluralityof sender systems. By becoming a member of the sender systems, recipientsystem 20B can act as a sending system and send encrypted messages toother recipient systems (e.g., as discussed above a system 20 can beconfigured as a sending system, a recipient system, or both).

At step 1004, in response to recipient system 20B accepting theinvitation and becoming a member of the plurality of sender systems,delivery manager 30 distributes certificates of other recipient systemsto recipient/sending system 20B. Recipient/sending system 20B stores thecertificates in local memory so that it can use the certificates in thefuture to send encrypted messages directly to the other recipientsystems.

FIG. 11 illustrates another example of a method for distribution of acertificate, according to certain embodiments. In certain embodiments,the method may be performed by delivery manager 30. At step 1102,delivery manager 30 receives a current certificate that DNS 40associates with the DNS name of recipient system 20B. For example, thecurrent certificate is obtained by periodically sending request messagesto DNS 40 according to a configured periodicity (such as every 5minutes, 1 hour, 1 day, 1 week or other suitable periodicity). Therequest messages request the current certificate associated with the DNSname of recipient system 20B.

At step 1104, delivery manager 30 determines that the currentcertificate differs from the previous certificate. The previouscertificate may refer to the version of recipient system 20B'scertificate that delivery manager 30 has previously stored in itscertificate repository for distribution to sending systems 20.

At step 1106, delivery manager 30 distributes the current certificate tothe plurality of sending systems 20. Delivery manager 30 may alsoinstruct the sending systems 20 to delete the previous key if thecurrent certificate is supposed to replace the previous key (it is alsopossible to keep both keys so that different keys can be used fordifferent purposes).

For purposes of example, the methods of FIGS. 6-11 have been describedin the context of using a certificate to encrypt a message. Certainembodiments perform analogous methods in the context of using acertificate to establish a transport layer security (TLS) for aconnection. For example, mail gateways can communicate at transportlevel, and certain embodiments use DANE protocol or other protocol toobtain certificates for establishing trust between two endpoints. Thatis, the cache can be extended to include transport layer certificatesthat can be applied to connections between mail gateways (regardless ofwhether or not S/MIME certificates are applied at the higher layer).

FIGS. 12-43 provide examples of methods for distributing TLScertificates, according to certain embodiments. FIGS. 12-13 aregenerally analogous to FIGS. 6-7, respectively. The methods may beperformed to communicate a TLS certificate associated with an endpoint.An endpoint may refer to any system (or component thereof) configured toestablish a TLS connection with another endpoint. For simplicity, FIGS.12-13 illustrate a first endpoint as sending system 20A, a secondendpoint as recipient system 20B, and another endpoint as sending system20N. In certain embodiments, the endpoints may comprise mail gateways 28within systems 20.

The method of FIG. 12 begins at step 1202 where a recipient system 20Bpublishes its TLS certificate with DNS 40. As an example, recipientsystem 20B may use DANE protocol to publish its certificate with DNS 40.Recipient system 20B may determine to publish its certificate with DNS40 in order to enable DNS 40 to provide the certificate to other systems20 in response to future requests for the certificate.

At step 1204, sending system 20A determines a certificate is needed toestablish a TLS connection with recipient system 20B. For example,sending system 20A determines that the certificate is needed if theconnection requires transport layer security and sending system 20A doesnot have a copy of recipient system 20B's TLS certificate stored inlocal memory.

At step 1206, sending system 20A requests recipient system 20B's TLScertificate from DNS 40. The request uses recipient system 20B's DNSname to identify the certificate being requested. Examples of DNS namesinclude domain names, fully qualified domain names, machine names, etc.In certain embodiments, the request may be configured according to DANEprotocol.

At step 1208, sending system 20A receives the TLS certificate that DNS40 associates with the DNS name of recipient system 20B. Sending system20A obtains recipient system 20B's TLS certificate from DNS 40 inreal-time when establishing a transport layer connection to recipientsystem 20B for which sending system 20A does not have the certificate.

At step 1210, sending system 20A uses recipient system 20B's TLScertificate (i.e., the certificate received from DNS 40 in step 1208) toestablish a TLS connection with recipient system 20B.

At step 1212, sending system 20A provides recipient system 20B's TLScertificate to delivery manager 30 for distribution to the other sendingsystems, such as sending system 20N. That is, in the embodiment of FIG.12, delivery manager 30 receives the TLS certificate that DNS 40associates with the DNS name of recipient system 20B via sending system20A.

At step 1214, delivery manager 30 distributes recipient system. 20B'scertificate to a plurality of sending systems 20. In certainembodiments, the certificate is distributed to the sending systems usingdistributed file version management technology. In certain embodiments,the certificate is distributed to the plurality of sending systemsaccording to a predetermined time period. For example, delivery manager30 may send updates to the sending systems at regular intervals based onthe pre-determined time period. Alternatively, delivery manager 30 maysend updates to the sending systems as delivery manager 30 receivesnew/updated certificates, without having to wait for the pre-determinedtime period. In certain embodiments, the certificate is made availableto the plurality of sending systems concurrently.

In the illustration, the plurality of sending systems 20 include sendingsystem 20N. Each sending system 20, such as sending system 20N, isconfigured to store recipient system 20B's certificate in its localmemory (step 1218) and, in response to a future determination toestablish a TLS connection with recipient system 20B, use recipientsystem 20B's TLS certificate from local memory to establish the TLSconnection (step 1220).

FIG. 13 illustrates another example of a method for distribution of acertificate, according to certain embodiments. The method begins at step1302 where a recipient system 20B publishes its TLS certificate with DNS40. As an example, recipient system 20B may use DANE protocol to publishits TLS certificate with DNS 40. Recipient system 20B may determine topublish its TLS certificate with DNS 40 in order to enable DNS 40 toprovide the TLS certificate to other systems 20 in response to futurerequests for the TLS certificate.

At step 1304, delivery manager 30 sends a request message to DNS 40. Therequest message requests the TLS certificate associated with the DNSname of recipient system 20B. As examples, delivery manager 30 may sendthe request message as part of a discovery procedure or in response todetermining that the certificate is needed by a sending system 20. Incertain embodiments, the request is sent according to DANE protocol.

At step 1306, delivery manager 30 receives the TLS certificate that DNS40 associates with the DNS name of recipient system 20B. In the exampleof FIG. 13, the certificate is received from DNS 40 as a result ofsending the request message in step 1304.

At step 1308 a-n, delivery manager 30 distributes recipient system 20B'sTLS certificate to a plurality of sending systems, such as sendingsystems 20A and 20N. In certain embodiments, the TLS certificate isdistributed to the sending systems using distributed file versionmanagement technology. In certain embodiments, the certificate isdistributed to the plurality of sending systems according to apre-determined time period. For example, delivery manager 30 may sendupdates to the sending systems at regular intervals based on thepre-determined time period. Alternatively, delivery manager 30 may sendupdates to the sending systems as delivery manager 30 receivesnew/updated certificates, without having to wait for the pre-determinedtime period. In certain embodiments, the certificate is made availableto the plurality of sending systems concurrently.

Each sending system 20 is configured to store the certificate in localmemory of the sending system (e.g., sending systems 20A and 20N storethe certificate in steps 1310 and 1312, respectively) and, in responseto a future determination to establish a TLS connection with therecipient system 20B, use the certificate from the local memory of thesending system to establish a TLS connection (e.g., sending system 20Auses the TLS certificate to establish a TLS connection in step 1314).

Methods analogous to those described with respect to FIG. 8 may beapplied to embodiments that encompass distribution of TLS certificates.For example, delivery manager 30 may initiate a discovery procedure inorder to discover whether DNS 40 has a certificate (or an updatedcertificate) associated with an endpoint for a TLS connection. As partof the discovery procedure, delivery manager 30 sends a request messageto DNS 40. The request message requests the certificate associated withthe DNS name of the endpoint. The discovery procedure can be initiatedand the request message sent without requiring the owner of the endpointto inform delivery manager 30 that the certificate exists. For example,delivery manager 30 may automatically check whether DNS 40 has thecertificate based on determining that another endpoint has established(or attempted to establish) a TLS connection with the endpoint. If DNS40 has a certificate for the endpoint, DNS 40 provides the certificatein response to receiving the request message from delivery manager 30.Delivery manager 30 receives the certificate that DNS 40 associates withthe DNS name of the endpoint. Delivery manger 30 distributes thecertificate to other endpoints which may then store the certificate inlocal memory for future use.

Methods analogous to those described with respect to FIG. 9 may beapplied to embodiments that encompass distribution of TLS certificates.For example, if delivery manger 30 determines that two endpoints failedto establish TLS for a connection, delivery manager 30 sends a requestmessage to DNS 40. The request message requests the certificateassociated with the DNS name of the endpoint whose certificate is neededto establish TLS. The request can be sent as part of a harvestingprocedure in which delivery manager 30 periodically reviews datareported from the plurality of endpoints, determines each instance inwhich any one of the endpoints failed to establish TLS, and if deliverymanager 30 does not already have the certificates required for thoseendpoints to establish TLS, harvests the certificates from DNS 40 (e.g.,by sending the request message to DNS 40).

If DNS 40 has a certificate for the requested endpoint, DNS 40 providesthe certificate in response to receiving the request message fromdelivery manager 30. Delivery manager 30 receives the certificate thatDNS 40 associates with the DNS name of the endpoint and distributes thecertificate to the other endpoints to be stored in local memory forfuture use.

Although the previous example has been described as being performed bydelivery manager 30, in other embodiments, the method could be performedby an endpoint itself. For example, if a first endpoint determines thatit is unable to establish a TLS connection with a second endpoint, thefirst endpoint may request the certificate from DNS 40, obtain thecertificate from DNS 40, and provide the certificate to delivery manger30 for distribution to other endpoints.

Methods analogous to those described with respect to FIG. 10 may beapplied to embodiments that encompass distribution of TLS certificates.For example, delivery manger 30 may send an invitation message to anendpoint. In certain embodiments, the invitation is considered to havebeen sent to the endpoint if the invitation is directed to the owner ofthe DNS name associated with the endpoint. The invitation messageinvites the endpoint to become a member of a system of endpoints. Bybecoming a member, the invited endpoint can obtain certificates fromdelivery manager 30 in order to establish TLS connections with otherendpoints in the system. In response to the invited endpoint acceptingthe invitation and becoming a member of the system of endpoints,delivery manager 30 distributes certificates of other endpoints. Theendpoint stores the certificates in local memory so that it can use thecertificates in the future to establish TLS connections with the otherendpoints.

Methods analogous to those described with respect to FIG. 11 may beapplied to embodiments that encompass distribution of TLS certificates.For example, delivery manager 30 receives a current TLS certificate thatDNS 40 associates with the DNS name of an endpoint. For example, thecurrent certificate is obtained by periodically sending request messagesto DNS 40 according to a configured periodicity (such as every 5minutes, 1 hour, 1 day, 1 week or other suitable periodicity). Therequest messages request the current certificate associated with the DNSname of the endpoint.

Delivery manager 30 receives the current TLS certificate from DNS 40 anddetermines that the current TLS certificate differs from the previousTLS certificate. The previous TLS certificate may refer to the versionof an endpoint's certificate that delivery manager 30 has previouslystored in its certificate repository for distribution to otherendpoints. In response, delivery manager 30 distributes the current TLScertificate to the plurality of endpoints. Delivery manager 30 may alsoinstruct the other endpoints to delete the previous TLS certificate ifthe current TLS certificate is supposed to replace the previous TLScertificate (it is also possible to keep both TLS certificates so thatdifferent certificates can be used for different purposes).

In any of the above-described embodiments, if delivery manager 30determines that there is a problem with recipient system 20B'scertificate provided by DNS 40 (e.g., S/MIME TLS certificate), deliverymanager 40 may notify recipient system 20B that there is a problem. Forexample, delivery manager 30 may notify recipient system 20B if thecertificate has expired, has an untrusted signature, or has any othererror. In certain embodiments, the notification is considered to havebeen sent to recipient system 20B if the notification is directed to theowner of the DNS name associated with recipient systems 20B.

Modifications, additions, or omissions may be made to the systems andapparatuses disclosed herein without departing from the scope of theinvention. The components of the systems and apparatuses may beintegrated or separated. Moreover, the operations of the systems andapparatuses may be performed by more, fewer, or other components.Additionally, operations of the systems and apparatuses may be performedusing any suitable logic comprising software, hardware, and/or otherlogic. As used in this document, “each” refers to each member of a setor each member of a subset of a set.

Modifications, additions, or omissions may be made to the methodsdisclosed herein without departing from the scope of the invention. Themethods may include more, fewer, or other steps. Additionally, steps maybe performed in any suitable order.

Some embodiments of the disclosure may provide one or more technicaladvantages. A technical advantage of certain embodiments may be theefficient management of recipient preferences within a network. Forexample, recipient preferences may be distributed to senders and storedin local memory associated with each sender. When a sender needs totransmit data to a recipient, the sender can use the recipientpreferences stored in local memory without having to ask a remoteresource, such as a central server or the recipient itself, for thepreferences. Thus, certain embodiments may reduce or eliminate latenciesand/or bandwidth penalties associated with having to ask a remoteresource for recipient preferences each time the sender needs totransmit data. Additionally, storing recipient preferences in localmemory may allow the sender to access and apply the preferences during atemporary absence of the remote resource.

In some embodiments, efficient management of recipient preferences mayfacilitate an ‘encrypt-if-you-can’ sending feature. According to thefeature, the sender checks the recipient preferences stored in localmemory to see if the recipient is advertising decryption capability. Ifthe recipient preferences indicate that the recipient is willing andable to decrypt data, the sender can encrypt messages to the recipienton an opportunistic basis in the interest of benevolent privacyprotection. Without a local store of the recipient preferences,execution of this feature may necessitate some network query to acentral resource for every message sent. Such per-message demands canresult in the consumption of more internet access bandwidth for policyexecution than that required to ultimately transmit the message. Thecombined effect of such bandwidth demands on the central resourcecharged with making the data available globally could materially impactthe cost and availability characteristics of the entire service.

Additional examples of technical advantages are discussed above in thesummary section.

Some embodiments may benefit from some, none, or all of theseadvantages. Other technical advantages may be readily ascertained by oneof ordinary skill in the art.

Although this disclosure has been described in terms of certainembodiments, alterations and permutations of the embodiments will beapparent to those skilled in the art. Accordingly, the above descriptionof the embodiments does not constrain this disclosure. Other changes,substitutions, and alterations are possible without departing from thespirit and scope of this disclosure, as defined by the following claims.

What is claimed is:
 1. A method for use in a delivery manager, themethod comprising: Receiving, at a delivery manager, from a firstsending system of a plurality of sending systems, a certificate that aDomain Name Service (DNS) associates with a DNS name of a recipientsystem; distributing the certificate to the plurality of sending systemsin response to the delivery manager receiving the certificate, eachsending system configured to: store the certificate in a local memory ofthe sending system; in response to a future determination to send anencrypted message to the recipient system, use the certificate from thelocal memory of the sending system to perform encryption; and send theencrypted message directly to the recipient system; and the firstsending system configured to: obtain the certificate from the DNS inreal-time when sending a message to the recipient system for which thefirst sending system does not have the certificate; and provide thecertificate to the delivery manager for distribution to the othersending systems.
 2. A system, comprising: a delivery manager and aplurality of sending systems, the delivery manager comprising: aninterface configured to receive, from a first sending system of theplurality of sending systems, a certificate that a Domain Name Service(DNS) associates with a DNS name of a recipient system; and processingcircuitry configured to distribute the certificate to the plurality ofsending systems in response to the delivery manager receiving a new orupdated certificate; wherein each sending system is configured to: storethe certificate in a local memory of the sending system; in response toa future determination to send an encrypted message to the recipientsystem, use the certificate from the local memory of the sending systemto perform encryption; and send the encrypted message directly to therecipient system; and the first sending system configured to: obtain thecertificate from the DNS in real-time when sending a message to therecipient system for which the first sending system does not have thecertificate; and provide the certificate to the delivery manager fordistribution to the other sending systems.
 3. The system of claim 2,wherein the DNS name of the recipient system corresponds to anindividual mail client.
 4. The system of claim 2, wherein the DNS nameof the recipient system corresponds to a mail transfer agent.
 5. Thesystem of claim 2, the processing circuitry further configured to: senda request message from the delivery manager to the DNS, wherein therequest message requests the certificate associated with the DNS name ofthe recipient system; and wherein the interface receives the certificateas a result of the processing circuitry sending the request message. 6.The system of claim 5, wherein the request message is sent according toDNS-based Authentication of Named Entities (DANE) protocol.
 7. Thesystem of claim 5, wherein the processing circuitry is furtherconfigured to initiate a discovery procedure such that the requestmessage is sent to the DNS without requiring the recipient system toinform the delivery manager that the certificate exists.
 8. The systemof claim 5, wherein the processing circuitry is configured to send therequest message in response to a determination that the sending systemfailed to send the encrypted message directly to the recipient system.9. The system of claim 8, wherein the determination that the sendingsystem failed to send the encrypted message directly to the recipientsystem is made based on data reported from the sending system.
 10. Thesystem of claim 2, the processing circuitry further configured to notifythe recipient system in response to the delivery manager determiningthat there is a problem with the certificate received from the DNS. 11.The system of claim 2, the processing circuitry further configured to:send an invitation message to the recipient system, wherein theinvitation message invites the recipient system to become a member ofthe plurality of sender systems.
 12. The system of claim 11, wherein thedelivery manager further comprises a certificate repository comprisingother certificates associated with other recipient systems, and wherein,in response to the recipient system becoming a member of the pluralityof sender systems, the processing circuitry is further configured todistribute the other certificates to the recipient system.
 13. Thesystem of claim 2, the processing circuitry further configured to:receive a current certificate that the DNS associates with the DNS nameof the recipient system; determine that the current certificate differsfrom the previous certificate; and distribute the current certificate tothe plurality of sending systems.
 14. The system of claim 13, whereinthe processing circuitry is further configured to periodically sendrequest messages to the DNS, wherein the request messages request thecurrent certificate associated with the DNS name of the recipientsystem, and the current certificate is obtained as a result ofperiodically sending the request messages to the DNS.
 15. The system ofclaim 2, wherein the processing circuitry is configured to distributethe certificate to the plurality of sending systems according to regularintervals.
 16. The system of claim 2, wherein the certificate comprisesone or more of: a key identifier, a public key, information about aversion, and a signature.
 17. The system of claim 2, wherein theprocessing circuitry is configured to make the certificate available tothe plurality of sending systems concurrently without having to waituntil a time when each respective sending system begins processing thatrequires the certificate.
 18. The system of claim 2, wherein theprocessing circuitry is configured to use distributed file versionmanagement technology to distribute the certificate to the sendingsystems.
 19. A non-transitory computer readable medium storing logicthat, when executed by processing circuitry of a delivery manager, isoperable to cause the delivery manager to perform actions comprising:receiving, at a delivery manager, from a first sending system of aplurality of sending systems, a certificate that a Domain Name Service(DNS) associates with a DNS name of a recipient system; distributing thecertificate to the plurality of sending systems in response to thedelivery manager receiving the certificate, each sending systemconfigured to: store the certificate in a local memory of the sendingsystem; in response to a future determination to send an encryptedmessage to the recipient system, use the certificate from the localmemory of the sending system to perform encryption; and send theencrypted message directly to the recipient system; and wherein, thefirst sending system is configured to: obtain the certificate from theDNS in real-time when sending a message to the recipient system forwhich the first sending system does not have the certificate; andprovide the certificate to the delivery manager for distribution to theother sending systems.